The invention relates to a method for managing an electrical energy generation facility comprising an electrical energy storage device.
In this type of facility, the storage device is used to store electrical energy generated by a generation device comprised in the facility, for example when more energy is generated than is consumed by equipment connected to the output of the facility. Conversely, the energy stored in the storage device is output to the equipment in order to supplement the generated energy when the latter is insufficient to supply to the equipment.
To avoid certain phenomena of degradation and shortened service life of the storage device, occurring due to usage conditions beyond its optimum operating envelope, it is preferable to have precise control over the charging and discharging of this device.
In this context, it is known to regulate the charging and discharging of the storage device according to the voltage it presents and which provides information concerning the amount of electrical energy it contains. This amount is then made visible by a display device showing colors which each correspond to a range of available energy, for example green for a high level of energy, orange for a moderate level, and red for a low level.
This practice presents a major problem: the discharge currents generally used do not allow transitioning between the high level and the moderate level until the discharge percentage is between 60% and 80%, which means a lack of visibility in the 15%-50% discharge range, corresponding to one day of autonomy, keeping in mind that such autonomy is generally from two days to a week. A 15% discharge thus corresponds to one day of autonomy when the storage device has an autonomy of seven days, and 50% discharge corresponds to when the storage device has an autonomy of two days.
To improve the situation, it is known to compare these voltage measurements with measurements of the discharge current. For a given charge state, the greater the discharge current the lower the measured voltage. However, these quantities, and in particular the voltage, are affected by external factors such as temperature. To account for these effects which are difficult to model, manufacturers record a series of data charts. These charts correspond to fixed situations that may substantially differ from actual situations, particularly due to transient effects. In addition, the behavior of the storage device changes with age, which these charts do not take into account.
To remedy these problems, it is known to calculate the ampere-hours entering and leaving the storage device and to relate these ampere-hours to the capacity of the storage device. However, there is uncertainty in this method due to the unpredictable nature of the variations in current efficiency during the charge and discharge reactions. This gives rise to significant deviations from the estimated charge state when the charge state remains within the blind area of the voltage measurements. An adjustment must then be made when the charge state leaves this blind area. However, the deviations that occur may be such that readjustments to the charge state of the storage device by several tens of percentage points may be necessary, which is inconsistent with a precise evaluation and control of the charging and discharging of the storage device and an operation of said device within its optimum envelope.